Signaling system.



No. 818,244. PATENT'ED APR. 17 1906.

J. L. HALI SIGNALING SYSTEM.

APPLICATION FILED SEPT. 15. 1904 2 SHEETS-SHEET 1 ATT'Y.

INVENTEIR,

J. L. HALL.

SIGNALING SYSTEM. APPLIOATION PILED'SEP'I'.15, 1904.

- 2 SHEETS-BHEET 2.

BY I

ATTY..

PATENTBD APR. 17, 1906.

.- thus be accurately followed on the chart. If so desired, thechart'maybe subdivided into UNITED STATES,

PATENT OFFHE.

JOHN L. HALL, OFSCHENECTADY, NEW YORK, ASSlGN-OR T GENERAL ELECTRICCOMPANY, A CORPORATION or NEW YORK.

SIGNALING svsrzm.

. This invention relates-to si a1 s stems,

. and more particularly to that c ass 0 signal- 10 ing devices known asrange-finders, and is particularly useful in military and navaloperations-for giving an accurate and practlcally continuous indicationof "the position of a moving object.

The invention consists ofthe combination of two ormore transmit i inginstruments suitablymounted to command the field of opera-' tions andreceiving instruments corresponding to the transmitting instrument'smounted to command a chart of the field in the same relation thereto asthe transmitting instruments are to the field itself. Each transmitteris provided with an' observing instrument delicately constructed topermit it to be accurately trained on the objective and with a rotatablemember driven by a suitable motor'yand the receiver corres endingthereto is rotated in synchronism with the rotatable member of thetransmitter and in the same angular relation to the field shown on thechart as-the rotatable member is to the actual field. Once in eachrevolution of the a "rotating member of the transmitter an electriccircuit is closed, the instant of closure depending on the exactposition of the observing. instrument, and the closure of this circuitcauses the receiver to give. instantaneously an indication on. the chartcorres onding direction to the position of the 0 given by flashing aline of light across the chart, and as two Hairs of instruments areoperated together t e intersectionof the lines oflight gives theposition of the. objective:

' The instruments are rotated rapidly, so that 'the flashes occur atvery'brief intervals,- thus makm the indications practically continueposltlon'of a moving ob ectiV e can squares or rectangles of relativelysmall dimansions and the mines, and the like a own thereon to enable theoperators tomake readings rapidly Specification of Letters Patent.Application filed September 15. 1904. Serial in. 224.655.

lngmstrument. Theindication is preferably ition of torpedoes,

Patented April 17, mos.

with great accuracy or to fire a mine when a vessel is shown to be overit. j

To rotate the receiver-and the rotatable member of the transmittersynchronously, I em y synchronous electric motors. Obvious y in a systemof this kind it essential "that the two rotatable members of a set notonly be rotated in synchronism but also that other, as one motor mightstart before the motor than in the ot ler while running as incurrentgeneratorwere used to supply the current for the armatures of thesynchronous motors and this'generator were brought up to speed-graduallyby a suitablemotor to increase the frequeny gradually until normalfrequency werereached, and thus bring the .motors u to speed, thecurrent from the generator w en first started would be so small that onemotor would be apt to start before the other, and the rotatable memberswould be angularly displaced, as before. In order to properly start themotors and bring. them up to speed together to maintain the desiredangular relation between the rojta'table members of the transmitter andreceiver driven thereby, I have provided an inverted rectifier,consisting ofa comn'lutator the segments of which are connected byresistances connected to mains from a source a of direct-current supplyand arrange brushes bearing on this commutator and connected to thecollector-rings for the armatures of the synchronous motors. Thesebrushes are dis equally distant from one i another a at the commutatorandare of such of the number of phases or- .which the syn- .chronousmotors were designed. By this If the alternating-current ar--'- other,and there mi ht be more slip in one duction-motors. -Again, if analternatingtheir angular relation must a ways he the might be angularlydisplaced relatively to the 3 a number as will give an altematingcurrent V means the frequency of the alternating current supplying thearmatures of the synchronous motors can be gradually increased until thefrequency for which the motors were. designed is reached, and sufficientcur-' rent is supplied by the rectifier even at the lowestfrequency toinsure starting the m0- tors instantly and bringingthem up to speedtogether to .preserve the proper angular re-- lation between therotatable parts driven thereby.

My invention therefore consists of a signaling set comprising atransmitter and a receiver, each having a rotatable part, means forrotating said parts in synchronism and in a definite angularrelation-that is to say, in similar phaseand' devices whereb thetransmitter causes the receiver to in icate a direction bearing adefinite relation to the position of the transmitter when said deviceswere operated.

It further comprises a transmitter and a receiver having rotatableparts, synchronous motors for driving them, and means for suplyingcurrent to the synchronous motors to bring them up to speed and to runthem when up to speed in such a manner as to always maintain 'a definiteangular relation or phase identity between the rotatable parts of thetransmitter and receiver driven thereby.

My invention further comprises other novel features which will bepointed out with particularity in the claims appended hereto.

The details of construction and the mode of operation of my improvedsignaling system will be better understood by referenceto the followingdescription, taken in connection with the accompanying drawings, whichshow the preferred embodiment of my invention.

In the drawings, Figure 1 is a view illustrating the general principlesof my invention. Fig. 2 is a sectional elevation-of the transmitter.Fig. 3 is a plan view of the receiver. Fig. 4 is a sectional elevationof the same. Fig. 5 is a section on line 5 5 of Fig. 4. Fig. 6 is amodified form of receiver, and Fig. 7. is a diagrammatic 'view showingthe electrical connections.

The general rinciples of the signaling apparatus will be est understoodfrom the diagram of Fig. 1, which shows a harbor on the shore of whichtwo transmitting instruments 1 and 2 are mounted in suitable positionsto have an unobstructed view of the entire harbor. These transmittersare provided with observing instruments, which may be the usualtelescopes such as are em loyed in surve having cross-hairs to eterminethe exact e of vision and arranged to turn on both a vertical and ahorizontal axis, so that they may be trained accurately'on anydesiredobject. Inany suitable-and rotected position a table is provided,on w 'chjs a,

squares, as shown.

the harbor drawn accurately subdivided, if 'desired, into Receivinginstruments 3 and 4 are mounted about the table, so as to bear to theharbor map ed out on the chart the same relation as t e transmittinginstruments Land 2 bear to the real harbor. The telescopes of thetransmitters 1 and 2 are brought to bear on the object, and theapparatus is so constructed that the receivers, which are rotated bysuitable motors, flash a line of light acros's the'chart every time theyarrive at a position parallel or having any other desired relation totheir respective transmitting instruments. The inchart having thereon antersection of these lines of light on the chart indicates .the harbor.

The transmitter consists of a base 5, in which is formed a bearing 6 fora sleeve 7, and'within this sleeve is a hollow shaft 8, carrying at itsupper end the plate 9, on which is position of the object in the mountedan observing instrument 10, such as a telescope. The telescope istrunnioned, as shown, to ermit movement on a horizontal axis, and shaft8 is loose in sleeve 7, so that it may be turned at will on a verticalaxis. The

plate 9 has an arm 11 depending. therefrom,

on the end of which is a metal c'brush 12,

and a wire 13 extends up throu h the hollow shaft 8 and is connected tobrus 12.

Sleeve 7 carries a circular plate 14, on the lower side of which is acollector-ring 15, with which a brush 16, mounted on' a block secured tothe base 5, cooperates to carry current to plate 14 while the latter isbeing rotated. On the upper side of plate 14 is a conducting-Se ment 17connected electrically to the col ectorrin 15. The circle of segment 17is preferably completed-by a segment of fiber 'or other insulatingmaterial to prevent jarring the parts when brush 12 leaves se ment 17.Near its lower end sleeve 7 is provi ed with a worm wheel 18, with whichmeshes a worm on the shaft of a s nchronous motor 19, suitably securedon the base 5.. It will thus be seen that the plate 14 is continuouslyrotated by the motor 19, that the telescope-and the arm 11 securedthereto can be turned by hand about vertical and horizontal axes to brinit to bear on the objective, and that the brus 12 on arm 11 sweeps overthe segment 17 once in each revolution of plate 14, so that during eachrevolution circuit is made and broken by the brush 12, and the instantat which this circuit is closed depends wholly upon the angular positionof the telescope.

The receiving instrument consists of a base 5, in the upper end of whichis formed a bear ing 20 for a sleeve 21. 'On the lowerendof this sleeveis a worm-wheel 22, with which meshes a worm 23 on the shaft of asynchronous motor 24, similar to the motor 19; At its upper end thesleeve 21 supports two parallel 0 s 25 25, which carry the mechanism forflashing the beam of light across the chart to give the desiredindication. This mechanism consists of a lamp, preferably anincandescent electric lamp, inclosed within a casing, a pivoted shutter.which normally closes an opening in the casing in front of the lamp, anelectromagnet for moving the shut-tenand a lens for focusing the ima eof the lamp filament upon the chart. Sli ably mounted upon the rods 25is a box or casing 26, in the lower part. of which are ways .27, inwhich the receptacle for the lamp 28 is mounted so that it may be movedback and forth by 'a suitable adg'ustin' -screw 29 to accuratelyposition it .15 be ore t e opening for the light-ra s. As 1 shown inFig. 4, this lamp is provide with a straight filament. I find inpractice that the limitmf speed at which the receiver can be rotate andthe indications given is the speed 20 at which the filament is bowed outby centrifugal force so much as to affect the accuracy 0 the indication.As the length of the lamp filament increases and decreases in responseto the, changes of temperature when circuit 2 5 through it is opened andclosed, I provide a a. coiled sprin 28., of conductin material, at

. one end of t e filament to hol the filament taut. In the front of thecasing 26 is an opening 30, (shown in dotted lines in Fig. 5,) and a 39shutter31, having a corresponding opening therein, is pivoted directlybelow opening 30.

Mounted behind the lamp in box 26 is an elec-. et 32, having a pivot-edarmature 33,'

'trorna WhlCh 1s plvotally connected to an extension 7 3 5 34 on theshutter 31.: These' parts are so arranged that when armature 33 of themagnet 32 is attracted the shutter 31 is turned on its pivot, so thatthe opening in the shutter passes across the opening in the box 26. 0' Acoiled spring is connected at one'end to armature 33 and "at the otherend to a stationary. post to retract the armature when I the ma et isdeenergized, thus carrying the shutter 31 back to the position shown inFig. 5' 5. A lens 36 is suitably mounted. to slide back and forth on therods 25 25 and in alinement -with the o ening30 inthe casing26- and thefilament o lamp 28. In order to accurately 7 focus the ra I of light onthe'h'art, I provide means byw 'ch the lamp 28 and lens 36 may be movedtoward or away from each other while the receiver is being rotated.Within the sleeve 21 is ashaft 37, extending. down throughauopening inthe base 5' and thread- 5'5 ed at its lower end. On-this threaded end isahand-wheel 38, held against vertical movement -hya lip on the base 5',as shown. At .its upper end. shaft 37 is provided with acircul'ar rack39, with which two pinions 40 and,

6c- 40', mounted] on short cross-shafta mesh. The pinions 40 and 40 areon opposite-sides of rack 39, so ,that when shaft 37 is raised orlowered by turnin the hand-wheel 38 the pinions and their s ts arerotated in o posite directions. On the shaft of each 0 the pinions 40 40are small ears 41 41', which mesh with racks on the ower sides of rods42 42, the former of which is rigid] connected to the lens 36 and thelatter to t ebox 26. It will'thu's be seen that rotating the hand-wheel38 to raise or lower shaft 37 operates, through the cireular rack 39,the two pinions 40 40' and ears 41 41', and the-rods 42 42, to. move theens and the lamp toward or away from each other, but that the rack 39ermits the rods 25 25' and the parts carrie thereby to be rotated freelywithout changing the relative positions of the-lens and lamp. Suitablymounted on the receiver are -four collector-rings 43, with which co- 8ooperate brushes 44, mounted on a block 45, secured on the base 5", Twoof these collector-rings carry the current 'to and from the magnet 32and the other two carry the current for the lamp 281 The lead's 46 fromthe brushes 44 are carried down through the base, as shown. v

.In Fig. 6 I have shown a modified form ofv receiver which has theadvantage that the arts are more compact and bowing of the ampingfilament b the rotation o the receiveris avoided. n thisreceiver thelamp is mounted horizontally in the top of the box, and immediatelybelow it is the lens. In'the base of the box. is an electromamietmounted in an incline position, as shown, and the piv oted armatureof this electromagnet carries on its upper face a mirror 47. Thelight-rays from lamp 28 are thrown onto the mirror and reflectedthereby, and when the magnet 32 is 10c i the retracted position by itsspring the lightrays are reflected above: the opening in the box, andwhen in the attracted position they are reflected below the o ening, sothat the flash upon the chart ison y an instantaneous 1 10 one,occurring while the armature is moving to the attracted position.

-As'described above, the rotatable parts of the transmittera'nd receiverare driven by synchronous motors. When these motors n5 are connected inthe samecircuit, they will of course rotate in 'synch-ronism; but in asystern-of the kind described it is emential that. the two rotatablemembers he also in'phase.

On account of the varying slip in synchrono nous motors when startedasinduction-mo; tors and the diilicultywhicli' would be encountered inobtaining the desired angular relation between the rotatable members ifauxiliary motors were used .to start-the synr: 5 chronousmotors andbring them up to speed it is" necessary that some means other than thoseusually employed in starting nous motors be provided to insum'the mam--tenance' of phase identity the two instruments. For this purpose Iprovide an inverted rectifier driven"b a suitable motor and suppliedwith current cm a source of direct-curre'nt supply. Thisis shown in Fig.7 of the drawings, in which 50 and 51 indicate positive and negativemains from a source of direct current, 52 a shunt-wound variablespeeddirect-current motor, and 53 a regulating-rheostat in the motor-circuitfor effecting the speed variations. On the shaft 49 of the motor 52 ismounted the inverted rectifier, consistin of two collector-rings 54 55,each connected to one of the mains 5O 51 byla stationary brush and acommutator 56, aving a plurality of segments, each connected to theadjacent segments through suitabl -proportioned resistances. The two colectorrings 54 and 55 are connected to the commutator 56 at diametricallyopposite points.- If the synchronous motors are two-phase motors, asshown herein, four stationary brushes 57 are employed bearing on thecommutator 56 and arranged to be equally distant one from another. bthose skilled in the art, this arrangement 02 the parts will give atwohase current on the four wires 57, leading om the brushes 57 .to thecollector-rings on the shafts of the As will be well understood.

two-phase synchronous motors 19 and 24;

It is obvious, however, that a different number of brushes 57 may bedisposed at equal distances apart about the commutator 56 in order togive an alternating current of a dif-' ferent number of phases andsynchronous motors constructed to run on such a circuit employed. Itwill also be seen that the variable-speed motor 52 permits varying thefrequenc of this two-phase current as desired. rom' the direct-currentmains 50 51 leads 58 59 are carried to the field. 60 of one of the snchronous motors and leads 61 62 to the fiel 63 of the other motor. Thelamp 28 in the receiver is connected across the loads 61 62. One side.of the coil of the electroma net 32 is connected to one of these leads,an from the other side a wire is carried'to the transmitter and extendsup through the hollow shaft 8 therein to the brush 12, which, as abovedescribed, bears during about onehalf of a revolution on the segment 17,which s connected, throu h the ring 15, to the opposite side of theirect-current circuit. In starting the s 'nchronous motors I close cir-'suit to the fie ds of the synchronous motors and to the invertedrectifier, start the motor 52 slowly, and gradually increase its speed,so as to gradually increase the frequency of the alternating-currentcircuit leading from the inverted rectifien. Wlu-u motor 52 is firststarted, the frequency being solow, the drop through the armatures ofthe synchronous motors is only that due to the resistance of the linesand conductors. When the motors are up to ipeed, however, and thefrequeue is norm the reactance in the motor armatures is high, due tothe relatively high frequency, and adds 'to the resistance of t e linesand conductors to cause a large dro in voltage through themotor-armatures.- or

this reason a voltage at the rectifier high enough to give the currentnecessary to run the motors when up to speed would cause the flow of amuch greater current when the motors are first started and might burnout the motor-armatures. I therefore insert a resistance 64 in one ofthe leads to the rectifier to cut down the current while the motors arestarting, and I arrange a switch 65 to cutout this resistance when themotors are u about one-half of normal s ed. On the s aft 49 of the motor52 and t e rectifier is a centrifugal ball-governor 66, arranged tothrow a switch-arm 65 when the motor reaches a rc determined speed to aosition in whic it cross-connects two stationary contacts 67, and thusshort-circuits the resistance 64.

The operation of .my improved signaling device as thus described is asfollows: The two receiving instruments are set u in the same relation tothe harbor mappe out on the chart as the transmittin' instruments are tothe'har bor which forms t e range, and the armatures of the synchronousmotors for the receiver and transmitter of each set are connected to aninverted rectifier, as shown in Fig. 7. The circuit of the mains 50 51from the source of direct-current supplyjs closed, thus closing circuitthrough the fields of the synchronous motors and through the resistance64, the inverted rectifier, and the armatures of the synchronous motors.This also closes circuit through the lamp 28- in the receiver and whenbrush 12 is in contact with segment-17 through the magnet-coil 32. Thearm of rheostat 53 is then moved slowly over the rheostat-contacts tostart motor 52 and bring it graduallyup to'speed, thus gradually increthe frequency of the armature-cir cuitof t e synchronous motors 19 and24. The rotation of the. armatures of the motors being directlyproportional to the frequenergr of the circuit 1n which they are connectthe motors 19 and 24 are brought up to speed gradually and ample currentis at all times supplied to the motor-armatures. The motors thereforestart together and come up to speed together, and when up to speed therotatable parts of the transmitter and receiver of a set are rotating insynchronism and a definite angular relation between them is at all timesmaintained. When the motor 52 has been speeded up somewhat,thecentrifugal governor 66 operates. to throw the switch 65, andthus'short-circuit-the resistance 64, so that the full-load current isadmitted to the armatures of the s nchronous motors. The operator ateach 0 the transmitting-stations 1 and 2 brings his telesco 10 to bearon the objective, and in moving the telescope to this position he movesthe arm 11,whioh carriesthecontact 12. As the plate 14 on thetransmltterrotates the, segment 17 comes under brush 12 once in each revolution and.the exact point in the revolution at which this-segment comes under thebrush is determined by the position of the telescope 10. Each time thisoccurs a circuit is closed from I the main 51, through ringaiid'segnient l 7,

through the coil 32 of the electromagnet on the receiver to the main 50,so that tlie iii-- position of the telescope. A similar flash is alsogivenby the'other receiving instrument v or instruments,- and theintersection of these flashes defines the osition of the objective. Thereceivers'and t 'e plates 14, on the transmitters are rotated ra idly,so that these flashes occur at very s ort intervals. The

indication is thus practically continuous and I may be followedaccurately on the chart. It

is entirely immaterial whether the two flashes occur simultaneously, assuccessive flashes follow each other so closely that no difliculty isencountered in determining the position of the objective even when theflashes from the two receivers occur alternately. The segment 17preferably extends over about one hundred and eighty degrees, so thatthe cirdeenergized after the receiver has turned onehalf a revolutionpast the position in which the flash wasgiven. When the magnet'isdenergized, the shutter 31 is retracted by s ring 35 and another flashis given; but this ash is in a direction 'awa from the chart, andtherefore does not con se the 0 erators. The 'use of an incandescentlamp straight filament offers many advantages. The source of light is afine line which may be positioned accurately before the opening in thecasing 26, so that when the lens is properly adjusted and the shutteropened the image of the filament is flashed u on the chart in a thinsharply-defined line w ich is plainly visible evenin daylight. By meansof the hahd-wheel 38 the position of the lamp and lens way be changedwhile the instruments are in operation in order to sharpl focus theimage of the filament upon the cliart. The opening 30 in the box' 26 isuncovered only for a minute interval, pr ferably about one- .h-undredthof a second, so that no error can arise due to the movement of thereceiver 'while the shutter-is open. 0

I have described my'improved signaling system herein as used inconnection with a horizontal base-line to indicate the osition of anobjective in theazimuth; but do not et 32 is broken and the magnetavinga ,wish to be understood as limited in any re spect, as the principlesof my invention are of broad application. Obviously angular-ins.

(-lination can be obtained iii-other than a horizontal plane. Also onetransmitter and receiver indicating the-azimuth may be used incombination with a. similar set of devices 1 operating llla verticalplane and using a vertical base-line, the intersection of the line in- Idicating the azimuth and that indicatin the angle of inclination givingthe range and the azimuth, and thus defining the position of theobjective. Again, combinations of azimuth and elevation indicatorsi'naybe employed lo obta n positions of the ob ective in two or morelanes for greater accuracy.

Furthermore, t e construction which I have herein shown and describedmay be greatl Y modified in many ways. I consider all suc modifications,however, within the spirit of my invention, and I aim to cover them inthe claims ap ended hereto.

. What claim as newfand desire to secure by Letters-Patent of the UnitedStates, is

l. Asignal system comprising a transmitter and a receiver eachhaving arotatable part, means for driving said parts synchromitter movableindependently of the rotatable part thereof, and means on the receiverfor indicating a direction bearing a definite relation to the positionof said observing instrument. I

2. A signal system comprising a transmitter and a receiver each having arotatable part, means for driving said parts synchronously and in adefinite angular relation, an observing instrument on the transmittermovable independently of the rotatable part. thereof, and means on thereceiver for indicating a direction bearing a definite relatlon to theposition of the observing instrument.

3. A signal'system comprising a'transmltter and a receiver each having arotatable part, means for driving said parts synchrolar relation,

*nously, an observing instrument on the trans- 1 thereof, and means onthe receiver for mdi catin once during each revolution of the rotatablepart ofthe receiver a direction bearing a definite relation to theposition of the observing instrument. 4 4. A signal system comprising atransmitter and .a receiver each having a rotatable part, means forrotating said parts synchronously and in a definite angular relation,and devices actuated by the transmitter for causing the receiver toindicate a direction bearing a definite relation .to the position of therotatable part of the transmitter when saidv devices were operated.

5. A signal system comprising a transmitter and a receiver each having arotatablepart, means for rotating said parts in synchro- -mitter and areceiver each havlng a rotatable part, means for driving said partssynchronism and in a definite angular relation, and devices actuated bythe transmitter for causing the receiver to indicate once in eachrevolution of the rotatable art thereof a'direction bearing a definitere ation to the position of the rotatable part of the transmitter whensaid devices were operated.

6. A signal system comprising a transmitter and a receiver each having arotatable part, means for rotating said parts synchronously, and meanscarried by the rotatable part of the receiver for giving an indicationof direction once in each rotation thereof.

7. A signal system comprising two transmitters and correspondingreceivers each having a rotatable part, means for drivin the rotatablepart of each transmitter an the receiver corresponding. thereto insynchronism and in a definite angular relation, and means on eachtransmitter for causing. its receiver to indicate a direction once ineach revolution thereof.

8. A signal system comprising two transmitters having parts thereonadapted to be trained on an objective, receivers corresponding to thetransmitters, a chart, and means on each receiver governed by thetransmitter corresponding thereto for flashirg a beam of light onto saidchart to indicate by the intersection of the two beams the position ofthe objective.

9 A signal system comprising two transmitters each provided with amovable observing instrument, receivers corresponding to thetransmitters each having a movable part, means for moving said parts, achart, and means on the movable part of each receiver governed by thetransmitter corresponding to that receiver for flashing a beam of lightonto the chart to give an indication.

10. A signal system comprising a transmitter and a receiver each havinga rotatable part, means for driving said parts synchronously and ina.definite an ular relation, means on the transmitter for c osing anelectric circuit, and means carried by the rotatable part of thereceiver and actuated on closure of said circuit to give an indication.

11. A signal system 00 rising a transnously and in a definite angularrelation,

means on the, transmitter 'for closing an electric circuit, and meanscarried by the rotatable part of the receiver and actuated onr closureof said circuitto indicate the angular" position of the movable part ofthe transmitter when said circuit was closed.

12. A signal system comprising a transmitter and a receiver each havinga rotatable part, motors for driving said parts synchronously-andin adefinite angular relation, a movable observing instrument on thetransmitter, means dependent upon the position of. said'instrument forclosing an electric circuit once in each revolution of the rotatablepart of the transmitter, and means on the ro tatable part of thereceiver actuated on closure of said circuit to give an indication.

13. A signal system comprising a transmitter and a receiver each havinga rotatable part, motors for driving said parts synchronously and in adefinite angular relation, a movable observing instrument on thetransmitter, means dependent upon the position of said instrument forclosing an electric circuit once in each revolution of the rotatablepart of the transmitter, and means carried by the rotatable part of thereceiver and actuated on closure of said circuit to indicate the'angular position of said instrument when the circuit was closed.

14. A signal system comprising a transmitter, a movable observinginstrument thereon, a receiver, a rotatable art thereon, a motor drivingthe same, an means carried by said rotatable part of the receiverarranged to givean indication each time it arrives a! a osition bearinga predetermined angular 1 ation to the position of said observinginstrument.

15. A signal system comprising a trans- .mitter and a recelver eachhaving a rotatable part, means for rotating said parts synchronously,devices on the rotatable part of the receiver for flashing a beam oflight to give a signal, and means on the transmitter governing saiddevices.

16. A signal system comprising a transmitter provided with. a movableobserving instrument adapted to be trained on an obj ective,'a receivercorres onding to the transmitter, and means on t e receiver overned bythe transmitter for flashing a cam of li ht.

l7. A signal system comprising a transmitter, a movable observinginstrument thereon', a receiver, a rotatable part thereon, a motordriving the same, a lamp carried by said part, and means for causingsaid lamp to glve an indication each time said rotatable part arrives ata position bearing apredetermined angular relation to the position ofsmdobservinginstrument,

18. A signal system comprising a trans mitter, a movable observinginstrument thereon, a receiver, a rotatablepart thereon, amo- ,tordriving the same, acasing having an opening therein on said part, alainpwithin the easing, an electromagnet, means operated thereby forpermitting the rays of l ght from said lamp to show through saidopening, and means lor'closing the circuit of said electromagnetdependent upon .the position of said observing instrument.

19. A signal s stem comprising a transmitter, a rotatab e member on thetransmit ter, means for driving the same, an observing instrument on thetransmitter movable independently of said rotatable member, means IIK ,mitter, a rotatab whereby an electric circuit is closed b thetransmitter once in each revolution 0 said member, and a receivinginstrument having parts actuated by the closure of said circuit. 20. Asignal system comprising a transe member on the transmitter, a motor fordriving the same, an observing instrument on the transmitter movableIndependently of said rotatable member, means whereby an electriccircuit is closed by the transmitteronce in each revolution of saidmember'at a point in the revolution depending upon the position oftheobserving instrument, and a receiving instrument havmg parts actuatedby the closure of said circult.

21. A signal system com rising a transmitter having a movable 0 servinginstrument thereon, a brush secured to the instrument and movabletherewith, a rotatable member, a motor driving the same,aconducting-piece carried by said member and ad apted to be engaged bysaid brush, a receiver having parts electrically actuated to indicate adirection bearing a definite relation to the position of the observinginstrument, and electrical connections between said parts and said brushand conducting-piece;

22. A signaling system comprising a transmitter, a rotatable memberthereon, a motor driving the same, a contact carried by said member, abrush cooperating with said contact once in each revolution of saidmember to close a signaling-circuit; means permitting movement of saidbrush, and the receiver having parts actuated to give an indication whensaid signaling-circuit is closed.

23. A signal system comprising a transmitter having means for closing anelectric circuit, a receiver, a rotatable member thereon, means fordriving the same, and means carried by said rotatable member and actuatcd by the closure of said circuit to give an indication.

24. A signal system comprising a transmitter ha means for closing anelectric thereby for permitting the rays of lig t from circuit, areceiver, a rotatable part thereon ,a motor dl'lVlJlg thesame, a casmhaving an I opening therein on said part, a. amp within t e casin anelectromagnet energized on closure 0 said circuit, and means 0 eratedsaid lamp to show through said opening.

25, A si 1' system comprising a transmitter having means for. closingand opening a circuit, a receiver, a rotatable part thereon, a motor thesame, a casing having an openingltherein onnsaid part, an incandescent eectric amphavging a straight filament withm the ass and meanscontrolling the admisfiitfrom the lamp through the openisclosedoropened.

26. A signal system comprising a trans-v nutter having means for rlosmgand openinga circuit, a receiver, a rotatable part thereon, a motor drving the same, an Incandescent electric lamp carried by said part andadapted to givca signaha spring within said lamp attached at one end tothe filament to hold the same in proper relation, and means controllingthe admission of light from the lanlp operated when said circuit isclosed or opene 27. A signal system comprising a transmitter havingmeans for closing and opening a circuit, a receiver, a rotatable partthereon,

a motor driving the same,'a casing having an opening therein'carried bysaid part, a lamp within the'casing, a shutter normally closing saidopening, and an electromagnct energize when said circuit is closed foroperating the shutter.

28. A signal system comprising a transmitter havingmeans for closing andopening a circuit, a receiver;a rotatable part thereon,

a motor driving the same, a casing having an o ening therein on saidpart, a lamp within t e casing, means operated when said circuit isclosed or opened for permitting the rays from the lamp to show throughsaid opening, a lens forfocusing the rays of light, and

means for adjustin the lens and lamp towar and away from eac other.

29. A signal system comprising a transmitter, a receiver, a rotatablepart thereon; a motor driving the same, a signal-lamp and a lens carriedb said rotatable part, means for adjusting the amp and lens toward andaway from each other while said part is beingro tated, andmeans on thetransmitter for controlling the admission of light from the lamp on thereceiver.

30. A signal system com rising a transmitter and a rece1ver, each avmg arotatable part, and means for starting said rotatable parts'from aposition of rest [0 ether,

bringing them up to speed together an =rotat-- ing t em in synchronismwhen up tospeedto maintain a definite phase relationbetween them.

31. A signal system com rising a transmitter and a receiver each avmg arotataj ble art, synchronous electric motors driving sai arts, and meansfor bringing said motors rom a position of rest up to speed together tomaintain a predetermined angular relation between the rotatable partsdriven by said motors.

-32. A signal system' comlprising a transmitter and a receiver eachaving a rotatable art, synchronous electric motors driving sai parts,means for supplying current to the armatures of said motors comprising arectifier, connections thereto from a source of direct-current supply,and electrical connections between sa d rectifier and-the armatures ofsaid synchronous motors.

33. A signal system comprising a'ltrans-' mitter and a receiver eachhaving a rotatable part, synchronous electric motors dri ing said parts,means for supplying current to the armatures of said-motors comprising arectifier, connections thereto from a source of direct-current supply,connections between the rectifier and the armatures of said motors, aresistance in one of said connections, and a switch forshort-circuitin'g the resistance.

34. A signal system comprising 'in combination, a transmitter and areceiver each having a rotatable part, synchronous motors driving saidparts, mains from a source of direct-currcnt sup 1 a variable-s )eedelectric motor connecteciihereto, a recti ier driven by said motor andconnected to said direct-current mains, and connections between therectifier and the armatures of the synchronous motors.

35. A si naling system comprisin .a plurality of ofiserving instrumentsat different oints, a miniature of the field of the observmg instrumentsat another point, and synchronized apparatus for directing two beams ofli ht to coordinately follow the movements of the observing instrumentsand locate by their point of intersection on the chart the position ofan ob'ective.

2 6. A si na ling system comprisin a plurality of 0 serving instrumentsat ifierent points, a miniature of the field of the observcommutator.and

ing instruments at another point, and synchronized apparatus fordirecting two planes of li ht to coordinately follow the movements ofthe observing instruments and locate by their point of intersection onthe chart the position of an objective.

37. In a si naling system. the combination of a signa ing device havinga rotatable portion, a synchronous motor driving the same, mainssupplying current to the motor. and means connected in said mains foradjusting the frequency of the alternating current supplied to saidsynchronous motor.

38. In a signaling system, the combination of a signaling device havinga rotatable portion, a synchronous motor driving the same, and means forvarying the frequency of the alternating current supplied to saidsynchronous motor comprisin a commutator having segments connects byresistances, and brushes bearin on the commutator, said rushes beingrelatively movable.

In witness whereof I have hereunto set my hand this 13th day ofSeptember, 1904.

' JOHN L. HALL.

Witnesses: BENJAMIN B. HULL,

HELEN ORFORD.

